Question: If $x \otimes y = x+8y$ and $x \bigtriangledown y = 2x-4$, find $1 \bigtriangledown (-1 \otimes 3)$.
We don't need to find $-1 \otimes 3$ because $x \bigtriangledown y$ depends only on the left operand. Find $1 \bigtriangledown y$ $ 1 \bigtriangledown y = (2)(1)-4$ $ \hphantom{1 \bigtriangledown y} = -2$.